Field of the Invention
The present invention relates to wireless communications and, more particularly, to a method and apparatus for transmitting and receiving sub-frames.
Related Art
With an increase in demands for the next generation mobile communications and high-capacity data communications, high-quality high-speed multimedia communication services are gradually needed. In particular, the next generation mobile communication system aims to provide a high-speed link service between a base station and a plurality of users. As demands for the development of digital multimedia technologies and high-speed wireless transmission increase, attempts to realize Gigabits per second (Gbps) wireless transmission in indoor and outdoor short-distance high-speed wireless data communications are proceeding in global technology developed countries. This means that beam forming systems tracking desired signals at high speed and having a higher gain between communications are gradually being required.
Beamforming is an antenna technology, in which energy radiated by antennas is concentrated in a certain direction on a space. The purpose of beamforming is to receive stronger signals in a desired direction or transfer signals with more focused energy in a desired direction. In particular, the beamforming systems are required to realize various types of beams with a higher gain for manufacturing high-speed and high-capacity wireless communication systems.
For example, the beamforming systems may be used in communications in a higher path loss band, such as high-speed mass data communications, various kinds of aeronautical satellite communications where smart antennas are used in satellites, aircrafts, or the like, for a plurality of users, etc. Therefore, beamforming communications are being studied in various fields, such as the next generation mobile communications, various kinds of radar, military and aerospace communications, indoor and inter-building high-speed data communications, Wireless Local Area Network (WLAN), Wireless Personal Area Network (WPAN), etc.